Interrupting unit for electric circuit breakers



March 2, 1954 c w, DRWER 2,671,146

INTERRUPTING UNIT FOR ELECTRIC CIRCUIT BREAKERS Filed Jan. 14, 1952 His Attorney Patented Mar. 2, 1954 UNITED STATES PATENT OFFICE IN TERRUPTIN G UNIT FOR ELECTRIC CIRGUIT BREAKERS Oyril.W. Driver, Secane, Fa a'ssignor to General: Electric Company, a= corporation-of New York Application January l i, 1952, Seria-PNo. 266334 llGlaimsa (Cl. 209*148) This invention; relates to interrupting units for electric circuit' breakers "and, more: particular- 1y.- t'o' an". arc;

su-lating plates for use in iconjunction with fluid. blast circuit breakers.

A bla'st ofi fluid, such as liquid" or: gas; supplied to the arc chute? of? a circuit breaker may result inwas'teful leakage of: fluid: through the opening in; the: wall of. the chute through which. the" mov Ac: principal objecti'of: this; invention: is to pro=- vi can improved interrupting; unit or are chute for. electric: circuit. breakers wherein provisionismadefforrminimizing: the leakageaofi fluidpres sure therefromthrough: an openingni'n awallthereof. through ciproca'ble.

Another? objectr of: thisinvention is-to provide" amimproved circuit breaker:- are: chute compris in'g'}: a plurality. ofzstackedi plates of: insulating material configured: and? arranged so a's tc form an: arcingxpassage having; an :a-rc'ing" region: gen erally or? trapezoidal cross-: section: andzanother 3:

a). generally" rectangular cross: section; thezregion of? rectangular? cross section-being: adapted -to' receive therethroughwmovable blarda regi'om (if type :contacti withzrelativelyaclos e:clearance.

tae't 'i's' reciprocable.

According to the invention, a" plurality" of cross section; a imovable. contact cficorrespondingly rectangula-i cross section being re'ciprocable music passage and; being of such site as: subchutet having a... corrugated arcing passage formedwithin a laminated stackofin which aimova'blewontact i's re Stillaanother object? of thisfinvelition isito'ipro .1:

The notches mzi the plates at one end ofthe chamber are stantially to bl'ock theexit' of rectangular cross section' so as to minimi'e the leakage of'gasblast products from said chute; According to a fur"- therfe'atureof: the invention; a plurality ofpairs of spaced nozzle half-plates having projectionsthereon are arranged with the" projecting por'- tions of the half plates'of each pair cooperating in spaced relation so as to constitute" a con-- verging-diverging nozzle with" each pair of these nozzle half -plates interposed between the" aforee said 'a'djace'n t notched' plates so as tofor'm-a plu rality of gas blast nozzles leading from a blast supply c'onduitand chute to atmosphere;

The invention"v will be better; understood from the following"description. taken in conjunction with the accompanying'drawing, in whichFig: 1 is aside View of an interrupting unit of a circuit breaker embodying the invention; Fig. 2 is an end view of a baflle stack forming the internal structure of an arc chuteconst'ructed according to the invention; Fig; baflie stack';.a'nd" Fig. 4 is a perspective view of the bafile stack showing certain of the plates thereoi exploded for of such constituent parts.

With reference to Figvl, the numeral I repre sents' a fixed finger-type contact which is dis-' posed forclamping. cooperation about the tip of a reciprocabl'e' fiat-blade sickle-type movable" Contact 2 is mounted at its lower contact 21 extremity; which is not shown, about" afixed pivot which: preferably. issecured to the blast" pip'e:3i'constructed of insulatingmaterial while a blast' valve,- not shown; controls the flow of arc-extinguishing fluid through pipe 3. Of course; suitable mechanical means for operating the -sick1e t'ype contact 2 andthe blast valve woul'd be' provided; Since" these parts form. no part of thepresentinvention they have been omitted from the drawing-for thesalke of sim-' plicity: Constituting a part ofthefixed contact I is a first 'teriiiinahwhile correspondingly suit-' able-means, not-shown, would be used for electric'all'y connecting the: movable contact 2 to a second terminal. of the circuit breaker. A resistance 4 may be connected tothe first terminal as indicated in the drawing. Secured to the upper-end" of the "blast pipe 3 is the interrupting unit or a'rc' chute generally designated by the numeral 5. Interrupting unit 5 is connected to the blast 'pipe z" by an appropriate packing gland arrangement 6 shown secured to the chute struc' ture by bolts 1; Supportforeach unit 5 is pro-- vided in the 'formm'f a p'air ci" horizontally dis exhausting through thearc disclosing the configuration posed supporting arms 8, which are mounted on a suitable frame structure, not shown.

Since in most cases it would be desirable to arrange a resistor for connection in parallel with the contacts of the interrupter, a resistor probe 9, which emerges from the side of the arc chute structure, is indicated in the drawings. Thus, with one terminal of the resistor 4 connected to the terminal of contact I, andwith the other terminal thereof connected to the resistor probe 9, the resistor 4 would be placed in the circuit in shunt with the arc drawn by contacts I and 2, and, in the event that an arc restrikes to the probe 9, the resistor 4 would be in series with such a restruck arc. The efiect of the resistor is to limit the magnitude of the arc current and to prevent re-establishment of the arc in known manner, as is set forth in U. S. Patent 2,284,842 to Prince et al. which is assigned to the assignee of this invention.

As is best seen in Fig. 4, the laminated internal structure of the interrupting unit 5 comprises a plurality of notched plates of insulating material designated by the letter A, together with a plurality of pairs of half-nozzle plates designated by the letters B and B. As will be obvious from the exploded section of Fig. 4, nozzle half-plates B, B are arranged in pairs with the enlarged ends C, C of each pair in spaced relation to constitute a nozzle throat designated by the letter 11 in the drawings. It will also be obvious from Fig. 4 that the notches in the plates A at the right-hand end of the unit are trapezoidal in cross section, the smaller base of which is the length y,

while the larger base portion is of length x. In

the stack of notched plates, the notch dimension or width 0: becomes progressively smaller as progression is made from right to left, as indicated at x, in Fig. 2, so that finally the larger base portion of the trapezoidally shaped notch has diminished so as to become equal to the smaller base 1/ as is designated in Figs. 2, 3 and 4, and therefore the notch becomes rectangular. By this means, the arcing passage generally designated by the numeral I0 is characterized by a relatively wide blasting zone [0a at the righthand end thereof adjacent the blast pipe 3 and with a diminished constricted cross section zone Hlb at the left-hand end thereof. Because the interrupting are invariably is extinguished in the wide blasting zone lfla, and blast cut-ofi occurs before the blade tip emerges from the arc chute, it will be understood that the blast carries substantially all the ionized products of arcing upwardly through the nozzle plates to exhaust through the top of the chute, and that a negligible minimum of ionized gases passes out from the chute end in the wake of the tip of the movable contact 2 as it moves to its open dotted position, inasmuch as the rectangular exit aperture H in the closure plate l2 has but small clearance about the blade 2. Such escape of the gases is minimized by the impedance to free flow of gas offered by the inwardly stepped edges of the notches as best seen in Fig. 2, which set up turbulence in this region of diminishing blade clearance in the arc passage.

It will also be understood form Figs. 3 and 4 that the spacing between the lower extremities of the nozzle half-plates designated by the letter 2 is larger than the corresponding base dimension :0 of the notches in the plates A, so that a plurality of side pockets l0 passage in, which aid by increasing the abovementioned turbulence. Thus, the passage l0 posare defined along the a said passage, means including disposed opposite sesses corrugated side walls which constitute guide channels for the blast as well as a sort of labyrinth fluid seal for minimizing the escape of fluid from around the blade 2 during circuit interrupting operations. Blast fluid is supplied to the arc chute N from the conduit 3 through an opening in the bottom closure wall l3, which wall is best indicated in Fig. 1.

As is best shown in Fig. 4, an end plate [4 is used to cover the right-hand surface of the interrupting unit; and, likewise, fiber coverings mainly constituted by the walls of the box-like arc chute, as shown in Fig. 1, are provided for the other surfaces of the laminated structure except for the top portion thereof which, as already explained, must be open for exhausting the ionized products of an interrupting operation to atmosphere. The plates comprising the unit 5 are maintained in position by any suitable means, such as the through-bolts l5. As in the aforesaid Prince et a1. patent, the upper edge of the movable contact blade is in close proximity to the bafiie edges constituted by the y dimension of the notched plates, as is indicated best in Fig. 2, in which the blade section is shown as a dotted rectangle.

While I have shown and described a particular embodiment of the invention, I do not wish to be limited thereto and intend in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent oi the United States is:

1. An electric circuit interrupter comprising an arcing passage, 9. pair of relatively movable contacts arranged to separate in said passage, one of said contacts being reciprocable along the length of said passage an inlet to said passage for supplying a blast of arc-extinguishing fluid thereto in a direction transverse to the direction of movement of said reciprocable contact, outlet means exhausting from said passage from said inlet, said passage having opposed side walls extending in the general direction of said blast from said inlet'to said outlet means, the space between said side walls forming the width of said passage, said side walls tapering gradually along the length of said passage irom said inlet toward said end thereby forming a passage of tapering width converging toward said end and having at its converging end a. constricted exit aperture closely surrounding said reciprocable contact, whereby said reciprocable contact substantially blocks escape of arcextinguishing fluid from said exit aperture during arc-extinguishing operation.

2. An electric circuit interrupter comprising an arcing chamber, a pair of relatively movable contacts arranged to separate in said chamber, one of said contacts being reciprocably movable in an opening through a wall of said chamber,

means including an inlet passage to said chamber for supplying a blast of fluid thereto in a direction transverseto the direction of movement of a movable one of said contacts, outlet means leading from said chamber and disposed in a wall thereof opposite from said inlet passage, the walls of said chamber being configured to define an arcing space adjacent said inlet passage which is substantially trapezoidal in cross section and to define a constricted region adjacent said opening which is substantially rectangular in cross;

section, said one contact being substantially recand out from an end o1- tangulan= inzcrossrsection andi'being: ori'suchi. size-z asrsubstantially torsfillisaid:constricted: region:

' 3%;An1electric1 ciicuit interruptencomprisingzan stantiallyi trapezoidal:.in cross; sectionand which issdisp'osed with its longen-base dimensionadja centisaidinlet' passage; and withits shorten base we dimension adjacent said-outlettmeans;. .thevregion1 of; said chamber-adjacent, said opening being substantially rectangular in; cross: section with one dimension substantially equal tosaid shorter base dimension.

4.. An electric circuit interrupter comprisingan arcing chamber, a pair of relatively movableiconetacts arranged to separateiin said chamber, one ofsaid contactslbeing reciprocably movable in anopening through a wall: of 7 said chamber,

meansincluding an inlet passage for said cham--- ber; for supplying a blast of fiuidthereto in a direction .transversetothe direction of .movement ohamovable one ofsaid; contacts, outlet means leading,fromsaidcliamber anddisposed in a wall thereof opposite fromsaid inlet passage, the Walls.

oflsaidschamber. being configured todeiine an arcing. space vadjacentsaid inlet. passagewhich .is.

substantially trapezoidal. in. cross section, and whichis disposedwith. its; longer base dimension adjacent said: inletpassage. and with .its, shorter baseedimension adjacentsaidoutlet. means, the.

region of said chamber. adjacent. said opening being substantially rectangular in cross section with one dimension substantially equal to said shorter basezdimension; the; portion, of. said chamber betweensaidarcing spaceandthe portion thereof'which is rectangularin' cross section beingz'trapezoidal in crosssection, the difference inlength. of. thebasedimensions. of a cross. sec.- tioniofi said chamber. beingtsubstantially proportionaLtovt-he distance.thereofyfrnnrlsaid;opening.

5-.- Anzelectric.circuitbreaker comprising a..,plu;- rality of. notchedplates: of; insulating material, said notched plates being stacked with the notched portions thereof forming an arcing chamber open along one side thereof, a plate of insulating material disposed adjacent said chamber and forming a closure for said one side thereof, a plurality of nozzle plates each having a projecting portion, said nozzle plates being arranged in pairs with the projecting portions of the plates of each pair in spaced relation, each pair of said nozzle plates being interposed between adjacent ones of said notched plates, the spaces between said projecting portions of said nozzle plates constituting a plurality of nozzles leading from said passage, means including an inlet in said closure for supplying a blast of fluid to said chamber, and a pair of relatively movable contacts arranged to separate in said chamber, one of said contacts being reciprocably movable through an end of said chamber remote from said inlet, the notches F the plates of'each: pair'in spacedrelation, each? pair of' said nozzlecplates being. interposedr'bes tween adjacentones of saiclnotched. plates, the-1-v spaces betweensaid projecting. portions. of said: nozzle plates constituting atpluralityof nozzles i leading from. said passage; means :including; an;

inlet insaidiclosure"iorzsupplyingsa blast of fluid: to saidchamber, and a p'airof relatively movable: contacts arrangedto:.separate: in said chamber,. one of said contactsbeing reciprocably movable through an end of saidchamber remote fromsaid, inlet, the notches in; said notched plates1being; substantiallytrapezoidal in. shape inthe regionl oirsaid inlet andbeing substantially rectangular; in shapeat said end of said chamberrremote from. said. inlet, the longer base dimension of: said? trapezoidal notches being: on the'side of said: chamber adjacent. said? closure and. the' shorter base dimension thereof beingon thesidetof'said; chamber adjacent said nozzles.

7. An. electric circuit breaker. comprising :a pl'u rality of notched plates: of insulating: material; said notched plates. being stacked with the: notched portions thereof. forming" an: arcing; chamber open alongonesidexthereof, a plate of insulating material disposed adjacent said chainiber. and forming alclosure:forrsaidoneiside theres of, a plurality of'nozzle plateszeach having: azproe jecting portion, saidznozzle platesbeing arranged; in pairs with the projectingportions ofthe plates of.'each.pair in. spaced relation, each'pair of said: nozzle plates J being interposed between adjacent ones of: said notched" plates; the-spacesbetween saidprojecting: porticnsof. said nozzle plates constituting a plurality" of nozzlesleading from said" passage, means includingfanzinlet in said closure. for; supplying a blast of fluid to said chamber, and. apair: of relatively movable. contacts; arrrangedto separate in;.said chamber, one of said; contacts being reciprocably movable through an. end of said chamber.v remote. from .saidtinlet,i thez notcheseinsaid.notchedzplatesbeingsubstantiallytrapezoidal in; shape: in thexregion of; saidiin-let: and being substantially rectangular in shape at said end of said chamber remote from said inlet, the longer base of said trapezoidal notches being on the side of said chamber adjacent said closure and the shorter base thereof being on the side of said chamber adjacent said nozzles, said shorter base 01- said trapezoidal notches being substantially equal in length to the corresponding base of said rectangular notches.

8. An electric circuit breaker comprising a plurality of notched plates of insulating material, said notched plates being stacked with the notched portions thereof forming an arcing chamber open along one side thereof, a plate of insulating material disposed adjacent said cham-- ber and forming a closure for said one side thereof, a plurality of nozzle plates each having a projecting portion, said nozzle plates being arranged in pairs with the projecting portions of the plates of each pair in spaced relation, each pair of said nozzle plates being interposed between adjacent ones of said notched plates, the spaces between said projecting portions of said nozzle plates constituting a plurality of nozzles leading from said passage, means including an inlet in said closure for supplying a blast of fluid to said chamber, and a pair of relatively movable contacts arranged to separate in said chamber, one of said contacts being reciprocably movable through an end of said chamber remote from said inlet, the notches in said notched plates being substantially trapezoidal in shape in the region of said inlet and being substantially rectangular in shape at said end of said chamber remote from said inlet, the longer, base of said trapezoidal notches being on the side of said chamber adjacent said closure and the shorter base thereof being on the side of said chamber adjacent said nozzles, said shorter base being substantially equal to the space between the projecting portions of each pair of said nozzle plates.

9. An electric circuit breaker comprising a plurality or" notched plates of insulating material, said notched plates being stacked with the notched portions thereof forming an arcing chamber open along one side thereof, a plate of insulating material disposed adjacent said chamber and forming a closure for said one side thereof, a plurality of nozzle plates each having a projecting portion, said nozzle plates being arranged in pairs with the projecting portions of the plates of each pair in spaced relation, each pair of said nozzle plates being interposed between adjacent ones of said notched plates, the spaces between said projecting portions of said nozzle plates constituting a plurality of nozzles leading from saidpassage, means including an inlet in said closure for supplying a blast of fluid to said chamber, and a pair of relatively movable contacts arranged to separate in said chamber, one of said contacts being reciprocably movable through an end of said chamber remote from said inlet, the notches in said notched plates being substantially trapezoidal in shape in the region of said inlet and being substantially rectangular in shape at said end of said chamber remote from said inlet, the longer base of said trapezoidal notches being on the side of said chamber adjacent said closure, and the shorter base thereof being on the side of said chamber adjacent said nozzles, said shorter base being substantially equal to the space between the projecting portions of each pair of said nozzle plates and the upstream surfaces of said projections being angularly disposed with respect to the side portions of said notches so as to define a plurality of small cavities along the length or said arcing chamber.

10. An arc chute for a fluid cross-blast type electric circuit breaker comprising a stack of insulating plates, alternate ones of said plates.

being notched so as to define an arcing passageway, the intervening plates between said notched plates constituting pairs or half-plates, each pair defining a flat convergent-divergent nozzle, the notches of said notched plates having a taper less than that of the convergent portion of said nozzles whereby side walls having corrugations are defined for said passageway, a blast inlet for said passageway, an open end for said passageway through which the movable contact of said circuit breaker is withdrawn, said corrugations constituting blast guide channels adjacent said inlet and a fluid-impeding labyrinth between said open end of said passageway.

11. An electric circuit interrupter comprising an arcing passage, a pair of relatively movable contacts arranged to separate in said passage,

one of said contacts being reciprocable along the length of said passage and out from an end or said passage, means including an inlet to saidpassage for supplying a blast of fluid thereto in a direction transverse to the direction of movement of the reciprocable contact, outlet means exhausting from said passage disposed opposite from said inlet, said passage having opposed side walls extending from said inlet to said outlet means to form an arcing space adjacent said inlet, said side walls tapering gradually along the length of said passage from said inlet toward said end so as to define a constricted exit aperture from said passage for said reciprocable contact and having corrugations therein extending transversely to the length of said passage, whereby said corrugations constitute blast guide channels adjacent said inlet and a fluid-impeding labyrinth adjacent said end.

CYRIL W. DRIVER.

References Cited in the file of this patent UNmD STATES PATENTS Number Name Date 1,840,292 Slepian Jan. 5, 1932 2,272,380 Ludwig et a1 Feb. 10, 1942 2,282,154 Bakken May 5, 1942 2,509,015 Pease May 23, 1950 2,586,290 Baker et a1 Feb. 19, 1952 

